Homeowner is confused about conflicting advice on required tankless water heater flow rate for a small house with 5 fixtures.

No simple, objective sizing tool that accounts for fixture count, household size, and local climate to recommend minimum GPM; plumber's advice conflicts with online product popularity.

Severity

2Mild

Willingness to Pay

implied

Added

May 22, 2026

Workarounds Described

'every unit I see on amazon and Home Depot that have the most reviews/purchases are anywhere from 6.6-8.0'
relies on plumber's advice despite conflicting with online data

Implied Software Gaps

Water heater sizing calculator that accounts for local climate, fixture count, and household size

App Concept

FlowRater Pro

FlowRater Pro is a mobile app that calculates the minimum GPM for a tankless water heater based on fixture count, household size, and location. It provides a clear, unbiased recommendation and explains the reasoning, bridging the gap between plumber intuition and consumer research.

Key Features

Input fixtures, household size, and zip code for climate adjustment
Calculates minimum GPM with explanation
Shows recommended units from major brands with purchase links
Compare multiple scenarios (current vs future family size)

Target Users: Homeowners and DIYers in the US selecting a tankless water heater for single-family homes

Revenue Model: Freemium (basic sizing free) with $2.99 per detailed report or $9.99/year subscription for unlimited scenarios and brand comparison

Existing Solutions Mentioned

searching Amazon and Home Depot reviews

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